最適化Tips 分岐条件の中で計算を行わない方が良い

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license : All rights reserved
modified : 2009-01-29 11:21:30

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<?xml version="1.0" encoding="utf-8" ?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" applicationComplete="appCompleteHandler(event)">
	<mx:Script>
	<![CDATA[
	import flash.events.MouseEvent;
	import mx.events.FlexEvent;
	import mx.controls.Alert;
	import flash.system.Capabilities;
	import flash.utils.getTimer;
	
	private var loopCount:int = 1000000;
	public function appCompleteHandler(event:FlexEvent):void{
		if(Capabilities.isDebugger){
			var msg:String = "デバッグ版のプレーヤを使用しています。正しいベンチマークの結果を得るにはリリース版を使用することをお勧めします。";
			Alert.show(msg, "インフォメーション");
		}
		console.text += "OS : " + Capabilities.os + "\n";
		console.text += "Vesion : " + Capabilities.version + "\n";
		console.text += "Type : " + Capabilities.playerType + "\n";
		Capabilities.isDebugger ? console.text += "Debug version\n" : null;
	}
	public function clickHandler(event:MouseEvent):void{
		startBenchmark();
	}
	public function clear(event:MouseEvent):void {
		console.text = "";
	}
	public function startBenchmark():void{
		var i:int;
		var tmp:Number = 0;
		console.text += "start benchimarking\n";
		
		i = 0;
		var time:int = getTimer();
		while (i++ < loopCount) {
			tmp *= tmp;
		}
		var dt:int
		dt = getTimer() - time;
		
		console.text += "ケース１：条件式内で計算を行う場合" + dt + "ms\n"; 
		
		i = 0;
		tmp = 0;
		time = getTimer();
		while(i < loopCount){
			i++;
			tmp *= tmp;
		}
		dt = getTimer() - time;
		console.text += "ケース１：条件式内で計算を行わない場合" + dt + "ms\n"; 
		
		i = 0;
		time = getTimer();
		while(i < loopCount){
			if ((tmp = Math.sin(i)) < 0) {
				
			}
			i++;
		}
		dt = getTimer() - time;
                console.text += "\n";
		console.text += "ケース２：条件式内で計算を行う場合" + dt + "ms\n";

i = 0;
		time = getTimer();
		while(i < loopCount){
			tmp = Math.sin(i);
			if(tmp < 0){
				
			}
			i++;
		}
		dt = getTimer() - time;
		console.text += "ケース２：条件式内で計算を行わない場合" + dt + "ms\n"; 
		
		console.text += "\n"; 
	}

]]>
	</mx:Script>
	<mx:VBox width="100%" height="100%">
		<mx:TextArea id="console" width="100%" height="100%"></mx:TextArea>
		<mx:HBox width="100%">
			<mx:Button label="Start" click="clickHandler(event)" />
			<mx:Button label="Clear" click="clear(event)" />
		</mx:HBox>
	</mx:VBox>
</mx:Application>

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